1. Field of the Invention
The present invention relates to a guide apparatus for guiding a palm to a position suitable for photographing, an image pickup apparatus, am image pickup system, and a guide method.
2. Description of the Related Art
In recent years, biometrics technology has increasingly been used as a substitute for authentication using a password or card. Fingerprint and iris, etc. have widely been used as biometrics authentication data. Within this field, “vein authentication”, which uses image recognition and optical technology to scan the normally invisible vein pattern of the palm, back of the hand, fingers, etc. has the properties of being highly accurate and highly resistant to counterfeiting, impersonation, and other dishonest actions.
Hemoglobin (reduced hemoglobin) in the red corpuscle flowing in a vein that has lost oxygen absorbs the near infrared radiation in the 760 nm wavelength region. Based on the above property, in the vein authentication, the palm is irradiated with the near infrared ray, and the location of veins is recognized by the degree of strength of the reflected near infrared ray. In particular, non-contact vein authentication system that performs authentication without giving user a feeling of reluctance by photographing veins of the palm in a non-contact manner is now widely used.
In order to perform the non-contact vein authentication, it is necessary for a user to place his or her palm on a specific position for registration of veins and to place the palm on the same position at authentication time. Thus, a guide apparatus for guiding the palm of the user to the same position both at the registration time and authentication time is used. In the following, a conventional guide apparatus will be described with reference to the accompanying drawings.
FIG. 11 is a view showing a conventional guide apparatus, and FIG. 12 is a view showing another conventional guide apparatus.
As shown in FIG. 11, a guide apparatus 5 has a wrist guide 201, a middle finger guide 202, and a non-contact sensor unit 40. The wrist guide 201 fixes the wrist of a user to be subjected to the vein authentication, middle finger guide 202 fixes the middle finger of the user, and non-contact sensor unit 40 photographs the palm of the user fixed by the wrist guide 201 and middle finger guide 202.
Further, as shown in FIG. 12, a guide apparatus 6 has a wrist guide 301′ a middle finger guide 302, a placement portion 303, and a non-contact sensor unit 40. The wrist guide 301 fixes the wrist of a user to be subjected to the vein authentication, middle finger guide 302 fixes the middle finger of the user, placement portion 303 guides the user's hand to be placed on the guide apparatus 6 in such a manner to spread his or her fingers, and non-contact sensor unit 40 photographs the palm of the user fixed by the wrist guide 301, middle finger guide 302, and placement portion 303.
As a prior art relating to the present invention, there is known a method and apparatus for positioning a living body (refer to, e.g., Patent Document 1: Jpn. Pat. Appln. Laid-Open Publication No. 11-47119)
However, in the guide apparatus 5, the position of the palm relative to the non-contact sensor unit 40 may change in the direction denoted by the arrow between the registration time and authentication time, as shown in FIG. 13 and, further, the degree of spread of the fingers may change between the registration time and authentication time. Further, in the guide apparatus 6, in the case where the width of the user's wrist is smaller than the width set by the wrist guide 301, the wrist guide 301 cannot fix the user's wrist as shown in FIG. 14, which may cause a change in the position of the user's wrist in the direction denoted by the arrow between the registration time and authentication time. As a result, the non-contact sensor unit 40 may photograph different portions of the palm between the registration time and authentication time. In this case, although the palm of the same user is subjected to the vein authentication, the vein pattern is determined to be different from that at the registration time, with the result that the relevant user is not authenticated.
In order to carry out the non-contact vein authentication smoothly, it is necessary to guide the user that he or she places his or her palm on the same position both at the registration time and authentication time. Further, the size of the palm or wrist differs greatly in individuals, so that a mechanism that enables alt users to place their palms on the same position relative to the non-contact sensor unit 40 is required.